1. Field of the Invention
This invention relates to a process for the production of alkyl and/or alkenyl oligoglycosides by acetalization of glycoses with fatty alcohols at elevated temperature in the presence of sulfomonocarboxylic acids as acidic catalysts, removal of the water of reaction and subsequent working up.
2. Statement of Related Art
Surface-active alkyl oligoglycosides, more particularly alkyl oligoglucosides, have long been known as valuable raw materials for the production of detergents and cosmetic products. They are normally produced either by direct acetalization of glycose with fatty alcohols ("direct synthesis") or via the intermediate stage of butyl glycosides which are subjected to transacetalization with fatty alcohols ("butanol route"), the water of reaction and any butanol being continuously removed from the reaction equilibrium. Working up of the crude alkyl oligoglycosides comprises neutralization of the products, removal of the excess fatty alcohol and, optionally, bleaching and conversion into paste form. EP 0 319 616 A1 and WO 90/03977 are cited as representative of the extensive prior art available.
The acetalization of glycoses or the transacetalization of glycosides with fatty alcohols always takes place in the presence of acidic catalysts. Typical examples of such catalysts are sulfuric acid [U.S. Pat. No. 3,974,138], alkyl benzenesulfonic acid [U.S. Pat. No. 5,003,057], p-toluenesulfonic acid [EP 0 301 298 A1]or sulfosuccinic acid [EP 0 415 192 ].
However, the use of the above-mentioned catalysts involves technical difficulties. Where sulfuric acid is used, partial carbonization of the glycose can occur; alkyl benzenesulfonic acid shows unsatisfactory catalytic activity; the use of p-toluenesulfonic acid results in incomplete yields and sulfosuccinic acid is not satisfactorily biodegradable.
Accordingly, the problem addressed by the present invention was to provide new catalysts for the acetalization of glycoses and for the transacetalization of glycosides with fatty alcohols which would be free from the disadvantages mentioned above.